<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>盒模型</title>
    <style>
        /* 清除默认的内外边距 */
        *{
            padding: 0;
            margin: 0;
        }
        /* 标准盒模型 */
        .box{
           width: 200px;
           height: 200px;
           padding: 20px;
           border: 10px solid red;
           margin: 10px;
        }
    </style>
</head>
<body>
    <div class="box"></div>
</body>
</html>